Java JDBC返回错误的生成键

Question

I am trying to get an ID of a newly inserted row from my database. After debugging and following the code step by step but it always returns a "0" value.

HashMap<String, String> response = new HashMap<String, String>();
    Integer generatedId = 0;
    try {
        ps = con.prepareStatement(query, Statement.RETURN_GENERATED_KEYS);
        ps.executeUpdate();
        rs = ps.getGeneratedKeys();
        rs.next();
        if (rs.isBeforeFirst()) {
            generatedId = rs.getInt(1);
        }
    } catch (SQLException e) {
        System.out.println(e.getMessage());
        response.put("STATUS", "ERROR");
    }

The code sits in a static method called update which accepts a string with SQL query String.

public static HashMap<String, String> update(String query)

Answer 1

Your code makes no sense.

If you call rs.next() , as you should, rs.isBeforeFirst() cannot possibly be true, and the following rs.getInt() would fail if it was.

Remove the test. It should really be if (rs.next()) etc.